Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w=map(int,input().split())
p=[list("#"*(w+2))]+[list("#"+input()+"#") for i in range(h)]+[list("#"*(w+2))]
s0,s1=1,1
g0,g1=h,w
p[s0][s1]=0
d=[(1,0),(-1,0),(0,1),(0,-1)]
q=deque([[s0,s1]])
while q:
    x,y=q.popleft()
    for dx,dy in d:
        if p[x+dx][y+dy]==".":
            p[x+dx][y+dy]=p[x][y]+1
            q.append([x+dx,y+dy])
if p[g0][g1]=='.':
    print(-1)
else:
    yy=0
    for i in range(1,h+1):
        for j in range(1,w+1):
            if p[i][j]=='#':
                yy+=1
    print(h*w-p[g0][g1]-yy-1)